1. Field of the Invention
This invention relates to new mitomycins and processes for production thereof.
2. Description of Prior Art
Mitomycins are generally known as compounds having anti-tumor, antibacterial activity. Representative mitomycins include mitomycin A, mitomycin B, mitomycin C, and porfiromycin, which are described in the Merck Index (Ninth Edition). In addition, Japanese Published Unexamined Patent Application No. 122797/1979 describes other mitomycins viz. mitomycin D and mitomycin E. These known mitomycins may be obtained by culturing a strain of Streptomyces caespitosus and have the following chemical structures:
______________________________________ ##STR1## X.sub.A 9 10 R.sub.D R.sub.E ______________________________________ Mitomycin A OCH.sub.3 CH.sub.3 H Mitomycin B OCH.sub.3 H CH.sub.3 Mitomycin C NH.sub.2 CH.sub.3 H Mitomycin D NH.sub.2 H CH.sub.3 Mitomycin E NH.sub.2 CH.sub.3 CH.sub.3 Porfiromycin NH.sub.2 CH.sub.3 CH.sub.3 ______________________________________
Various derivatives of these compounds are also known. For example, 1a-N-acetyl-mitomycin C (U.S. Pat. No. 3,514,452), 1a-N-butyryl-mitomycin C (U.S. Pat. No. 3,514,452), 7-ethylamino-7-demethoxy-mitomycin A (U.S. Pat. No. 3,514,452), 10-decarbamoyl-mitomycins A, B and C (U.S. Pat. No. 3,738,998) 1a-N-acetyl-10-decarbamoyl-mitomycin C (Japanese Published Examined Patent Application No. 17,279/1974), 1a-N-acetyl-10-decarbamoyl-10-p-toluene-sulfonyl-mitomycin C (Japanese Published Examined Patent Application No. 37,639/1972), 10-decarbamoyl-10-p-toluene-sulfonyl-porfiromycin (Japanese Published Examined Patent Application No. 37,639/1972), etc. are known. In addition, mitomycins having a double bond between 9- and 10-positions, other than those described in the present specification, are disclosed in commonly owned U.S. Patent Application Ser. No. 58,670 filed on July 18, 1979.
While the known mitomycins exhibit good activity, new antibacterial compounds are always in demand. To this end, the present inventors have found new mitomycins which exhibit good antibacterial activity.